What do wishbone bushes do

To optimize the way bushes work, these parts need to be flexible and sustainable. Take for instance the part shown in the video. This design change has structurally altered the appearance of the bush which also means the rubber mark which indicates the mounting position has been removed.

Due to the removal of the rubber mounting mark, extra care should be taken when fitting the new bush. A car bush system needs surveillance and when symptoms of expiration appear you should be prepared. Here are 4 sings of bad bushes that can help you:. Please review and accept our Privacy Policy before signing up for the newsletter. Find My Part. Products Light Vehicles Commercial Vehicles. Because the rubber has to deform to allow movement, the bushes effectively add rate to the suspension.

The rate increase is consistent though, since the rubber is of the same specification in each bush. Once the bush is fitted, you don't have to measure of check anything, because the movement comes from the rubber.

Just torque them up and away you go. The rubber also helps dampen a lot of the road vibrations from entering the car. They are difficult to fit. However, their biggest drawback comes as no surprise. Because the rubber permits rotational movement, it's perfectly logical that it will permit all kinds of other movements too. Although the majority of movement is torsional as it should be, the rubber will also permit a small amount of forwards and backwards movement wobble. The longer the wishbones are, the bigger a problem this will be, since the movement is multiplied at the wheel.

So the geometry of the car will all be moving around when the wishbone sees any kind of load. Not really a problem for a road car, but could be for a track car.

As described in the overview, metalastic bushes require a huge amount of force to fit, so they are not really a job for the DIY enthusiast. Worse still, they often take even more force to remove if they have been in there a while.

Lots of heat, swear words, and often a hacksaw!!! Typically you will need to remove the wishbone from the car, take it to a garage press, and then put around 10 tonnes of force into it to get it in or out. It's also very important to remember that metalastic bushes work by the rubber twisting, but because the rubber is bonded to the metal, it will only move so far before running out of movement going solid.

For this reason, it is imperative that these bushes are not torque tightened until the wheels are under their own weight. At this point you tighten the bolts which then locks the bushes to the wishbone brackets, and then they have the maximum amount of travel in both bump and droop directions before the rubber locks-out. A much more performance-orientated wishbone bush is nylon. Unlike the metalastic bush, they come in 3 parts as opposed to 1.

Each bush is made up of a steel crush tube just like what is at the centre of a metalastic bush , and two nylon pieces which are shaped like a top hat with a hole through the middle. The way in which nylon bushes work is different though. Instead of rubber being used to deform and permit movement, the movement is provided by the crush tube being allowed to rotate within the nylon.

The crush tube is a precision fit for the nylon, and a bearing is effectively formed. The crush tube remains fixed, while the nylon and wishbone rotates around it. The two nylon top-hats are pressed into the wishbone bush housing at either end, and then the crush tube passes through the entire assembly. The crush tube is marginally longer than the combined length of the nylon pieces when pressed into the wishbone. As a result, when fitted the crush tube is bolted tightly against the wishbone mounting bracket which locks the crush tube into place.

The wishbone and its nylon inserts are then free to rotate around the crush tube. The faces of the top hats will be very lightly in contact with the face of the wishbone brackets, but this is to prevent the bush twisting in a way it shouldn't. The end result is an almost frictionless wishbone motion, with virtually no deformation or undesirable geometry movement due to the nylon being solid.

There is also no increase in rate, unlike metalastic bushes. This makes it a very desirable choice for track cars. Providing the bushes have been manufactured well, they are relatively very easy to fit although be prepared to spend some time checking to make sure they are a perfect fit. Geometry is held almost perfectly since no deformation occurs, and no rate is added to the suspension during wishbone movement.

They can also be torqued up with the car in the air since the bearing is effectively degree. Because of the nylon, most of the road noise and vibration is transferred into the chassis. This could have undesirable effects long-term if the car is used on the road. Also, nylon bushes are a precision fit, and so you must be prepared to make sure that everything is perfect which can take time.

If you don't get them to fit well, you could end up with different rates being added at all 4 corners of the car due to stiction. The first job is to ensure that the top hats fit into the wishbone housing perfectly. This means removing all traces of the old bush from your wishbone bush carriers, or ideally running a reamer through them to get them to the exact required diameter to an ultra-accurate tolerance. If the top-hats do not fit snugly not too tight, not too loose , they may well deform slightly, which means the centre hole will become oval instead of round, and introduce friction into the rotation of the crush tube.

Also be sure that the nylon inserts are perfectly seated. Just check that the welds on the housing do not affect the seating of the nylon insert. If it's not perfectly flat, you'll get friction.

The Dremmel is a brilliant little tool here. Now insert the crush tube through the nylon. The crush tube should rotate freely in the bush without catching. It should also be a snug fit without being able to wobble. If it wobbles, this movement will be translated into the wishbone, multiplied by the length of the wishbone, and then translated into the wheel - very bad!

If the crush tube does not rotate, double-check the nylon inserts are a good fit. Lastly, check that the length of the crush tube is marginally longer than the nylon when fitted to the bush. You are looking for between a 0. So if your bush measures 40mm across, your crush tube should be a minimum of They ensure that there is no metal-to-metal contact.

It moreover, controls the amount of movement within these joints. Wishbone bushes are vital to the safety of your car, steering, and handling. Over time these bushes wear, and this is a common reason for MOT failures and increased tyre wear. Worn down suspension bushes can result in metal-to-metal contact of suspension parts.

This contact can inflict stress to these parts and cause them to wear down too. The parts that can become damaged, tend to be more expensive and harder to replace than the suspension bushes, which is why it is so important to replace them when they need replacing.

Drivers of a vehicle with worn suspension bushes may experience a lack of control in steering, as well as feeling a bumpier ride and less responsive breaking. Not only does this affect the driving experience, but it can also be dangerous to the driver. Controllability and breaking is a crucial part of any vehicle, and so suspension bushes need to be working to maximum efficiency.

Worn suspension bushes can also lead to abnormal creaking and clunking noises coming from a driven vehicle.